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N. B. CLARK & F. B. KING.

STEAM BOILER.

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N. B. CLARK 81; P. B. KING.

STEAM BOILBR.

Patented Dec.'15.`1891.

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No. 465,082. `Patented Deo. 15, 1891.

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ATTORNEY v "ne: noms :areas ce.. nom-umu., msumurau, n. c.

A limiten STATES ATENT OFFICE.

NATHAN B. CLARK- AND FRANK 13. KING, OF VASIIINGTON, DISTRICT OFCOLUMBIA.

STEAM-BOILER.

SPECIFICATION forming part of Letters Patent No. 465,082, dated December15, 1891.

Application filed October 4, 1890. Renewed November 14, 1891. Serial No.411,843. (No model.)

To all wiz/0m, it may concern:

Be it known that we', NATHAN B. CLARK and FRANK B. KING, residing atlVashington, District of Columbia, have invented certain new and usefulImprovements in Steam- Boilers, ot' which the following is aspecification, reference being had therein to the accompanying drawings.

This invention relates to steam-boilers of the kind which havewater-tubes for a considerable extent of the heating-surface.

The object of the invention is to produce a steam-boiler ot the generalcharacter described, in which the plates forming the shell of the waterand steam chambers, or either of them,shall merge into the tube-sheetstangentially, so as to secure great strength ot structure withoutimposing awkward stress on the outer rows of tubes or the employment ofstays to relieve such stresses; also, to stay the boiler internally in aconvenient manner; also, to reduce the quantity of water in a shell oflarge size; also, to improve the construction of the boiler in variousways.

Figure 1 is a partial end elevation and partial section of asteam-boiler embodying this invention. Fig.'2 is a central verticallongitudinal section of the boiler, Fig. 1. Fig.

3 is a top View and horizontal section just above the grate of Fig. 1.Fig. e is a side elevation, and Fig. 5 a section, of the series of tubesnext the tire, with their protecting .nre-bricks. Figs. 6 to 9 aresectional details of fastenings for the stays which connect the top andbottom members ot the boiler. Fig. 10 is a cross-section of a modifiedboiler. Fig. 11 is an elevation or plan of an excluder used in theboiler-chamber. Fig. 12 isa plan,and Fig. 13 an end elevation andsection on line A B, Fig. 12, of boiler member with excluder applied.Fig. 14 is a modiiication showing connection of steam-drum to topmember.

The letter A indicates the top member of the boiler. The shell of thismember is composed of a central arched plate l, turned down at itssides, as at 2, and there connected' to the inner edge of the side arch3. Arch 3 has a turnedin edge 4, proximate to the part 2 of plate 1, andthe edges are secured together and to stays leading to the lower boilermember. There will be a man-hole m through plates 2 LI. rlhe arch iscontinued and merged in and secured to a straight, or nearly straight,tube-sheet 5, which tube-sheet is tangential to the curve of the arch,the tubesheets extending at an angle from the horizontal.

The two sides of the boiler are alike, and the two tube-sheets 5 connectacross the median line 6 of the boiler under arch 1 by a curved surface,preferably swept by the same radius and from the same center as the arcA, the same radius being preferably that 0E are 3 also. The plates ortube-sheets 5 extend tangentially downward and toward the center. Vater-tubes' 7 extend from these to tube-sheets 15 of the lower boilermembers B. Along the central or other convenient line of the tube-sheetsa series ot' large tubes 8 connect'lthe tube-sheets 5 and 15, and theties passthrough these large tubes, leaving space around the ties forthe passage ot water.

The bottom members B of the boiler have the shell-plates 1l arched orcurved, and then by a reiiex curve the plates are brought round to forma second arch 13. Both arches are continued until merged into thetangential tube-sheet 15.

The stays 2O may be rods with flattened ends riveted to or between theplates 2 and 4 in the upper member and connected to suitable supportsoutside the lower boiler meniber. These supports may be bow-plates 22,having a fiat side 23 resting in the reflex curve of the bottom memberB.

The stay-rods 2O pass through the bottom plate of the boiler member B,and, as shown in Figs. S and 9, nuts 2e are applied to the threads onthe rods outside the tlat bars of the bow-plates. The passages roundrods 20 are closed by grommets 2G, held dow'n by nuts 27.

As a modication, the bow-plates 22 may have internal threads or nuts 29,into which the rods 2O are secured before the upper ends are riveted.(See Figs 6 and 7.)

The tube-sheets 5 5 are inclined and paie allel to the sheetsY 15. Thetubes 7 and 8 connect the sheets 5 and 15 at right angles IOO to eachsheet and are therefore inclined inwardly at their upper ends, and aspace C is left between the tubes of the right and left handboiler-section.' This space C receives the fire-grate 3() and theash-pit 3l. (See Fig. l.)

The intense heat of the fire would soon burn out the row of tubes 7 nextthe fire if the same were not protected. XVe therefore cover the innerrow of tubes 7 with fire-bricks 40 to form a shield and to establish acirculation of gases to the back of the furnace, returning among thetubes. These ire`-bricks are made with a flat front and are hollowed atone side. The cutaway portion corresponds with the inclosed side of tube7. Two bricks turned together, as in Fig. 5, will fill the space betweentwo of the tubes 7. The bricks do not reach to the top of the tubes 7when the boiler is complete, asshown in Figs. l and 2,but may be enteredat the top of the tubes and passed down. Two bricks placed between thepipes, as in Fig. 5, will lock each other, so. that neither can beremoved; but by lifting one brick up, so that its extension 4l is abovethe similar extension of its fellow, the bricks can be readily removed.

The top of the furnacewill be covered' with a shield or layer oftire-bricks 44 some little distance below the plates 5, to protect saidplates from the intense heat of the flame. The end plates 48 and 49 ofthe top and bottom members A B are portions of spherical surfaces. Thecentral portion of the top member A is connected by a downcast pipe 50with both the bottom members B, pipe 50 having two branches 5l, leading,respectively, to the proximate sides of the two lower members B. Thisdowncast will-take water from the deep body of water at the middle ofthe top member and conveyit to the bottom member, and the waterwill passup through tubes 7 and 8,when the boiler is heated, on principles ofcirculation well known in this art.

The parts so far described go to make up a single boiler. Any number ofboilers of this kind may be arranged in battery, a convenientarrangement being shown in Fig. l, dotted lines. The outer tubes of eachboiler may be protected by bricks 40X, and a furnace 30X, covered by anarch 44X, may be arranged between each pair of boilers. Otherwise thesides of the boiler will be inclosed with any suitable casing, such asremovable metal panels faced with asbest us and placed against the outerrows of tubes, and the rear of the boiler Will have a casing 53 betweenthe boiler and the downcast.

The fire from the grate 30 passes back and around the wall or shieldformed by bricks 40, and then passes to the front of the boiler amongthe tubes 7 and 8, (see arrow, Fig. 2,) and out at the uptake 55, therebeing an uptake at each side of the boiler, preferably leading to asingle stack.

In the modification Fig. 10 an arrangement is shown in which the tirepasses from the cen*- tral grate 31X to both sides between the smalltubes and so to uptake 55X. The top and bottom members of the boilershave more than two arches at each side of the center, which is withinthe spirit of the invention.

It is desirable that the members A and B of the boiler be large enoughto admit a man, and man-hole plates are provided for the pur-A pose; butfor some uses this gives an excess of water-space to the boiler. Vhendesirable to reduce weight, we insert in. the sections B (and in thelower part of section A) very thin metallic cylinders or excluders GO,attached to the man-hole plat-es 6l and 'extending nearlyto the rearofthe water-chambers. The rear ends 63 of these excluders are preferablyrounded or pointed, so as not to interfere with the How of water from orto the downcast. The excluders are each provided with a small steam-pipe64, leading to the steam-space in the boiler, and a drain-pipe G5,leading to the feed-suction pipe or any convenient place where there isa reduced pressure. By this construction the steampressure withinthe-excluder equals the wa-' ter-pressure outside thereof. Consequentlythe shell of the excluder may be made very light, yet the water will beexcluded from the boiler member to an extent equal to the size of theexcluder. When the man-hole plate is removed from the boiler, theexcluder will be removed with it, so that free access may be had to theinterior of the boiler.

The outer or inner tubes 7 may be readily removed and replaced when thecasing or bricks next them are removed. Tubes nearer the tubes 8 can beremoved and replaced by rst removing the outer tubes in the row untilthe defective tube is reached; or the tubes may be arranged in doublecolumns with alternate spaces, as shown in Fig. 3, and tubes may bepassed in the spaces and swung into position to be expanded in thetube-sheets.

Wie consider the merging of the shell into the tube-sheet tangentiallyas particularly valuable in boilers of this class. This prevents tensilestress on the outer row of tubes, which connect the boiler members, andobviates the use of external stays parallel to the tubes.

It will be understood that the claims are intended to cover equivalentconstruction.

In Fig. 14 the top member is shown as nearly a duplication of the bottommember. The top sheets 2 are made to join the sheets 3 by a reflexcurve, as in the bottom member. .This permits the stays 2O to passthrough both top and bottom members, and nuts 24 may be applied on bothends of the rod.

The construction in Fig. 14 provides steam room at top of the boiler byconnecting a steam-drum with each arch of the upper member of the boilerby pipes 7l, as many in number as may be necessary.

Steam will be taken from the steam-dome IIO IZO

have arched ends, as do the arched sections forming the boiler members.

That We claim is-- l. In a steam-boiler, a single top member composed ofarched cover-plates and iiat tubesheets and two bottom members of archedshells and flat tube-sheets andinclinedwatertubes connecting theproximate faces of the tube-sheets, substantially as described.

2. The boiler member composed of arched shell-plates and a fiattube-sheet merging with and tangential to the shell-plates andwatertubes connecting said member to another boiler member,substantially as described.

The combination of the top and bottom members of the boiler connected bytubes, a furnace next the tubes, and fire-bricks alternately cut away onopposite sides lying between the tubes and interlocking therewith,substantially as described.

4. The combination of the top member having its shell composed of archedplates and a tangential tube-sheet, the bottom member composed of refiexcurved plates and a tangential tube sheet, tubes connecting saidtube-sheets, bow-pieces resting in the reflex curve of the bottommember, and stays passing through said tubes and secured to saidbow-pieces and to the top member, substantially as described.

5. The combination of the top member having its shell composed of reflexcurved plates and a tangential tube-sheet, a bottom member of similarconstruction, connecting watertubes, and a stay passing through bothboiler members and a connecting-tube and secured outside the boilermembers.

6. The combination of the top member having a reflex curve in its shell,a bottom member having a reflex curve in its shell, watertubesconnecting these members, bow-pieces resting in the curve of the shell,and stays passing through both boiler members and having nutengagement-with the bow-pieces, substantially as described.

7. The combination ot"V the upper boiler member having a series ofarches arranged side by side and communicating witlreach other, asdescribed, with a steam-drum above the arches and connected to each archby a suitable pipe, substantially as described.

S. The combination, with the top shell and the reflex curved bottomplate, of the bowpiece resting in said curve outside the shell, and astay having nut engagement with said bow-piece and passing inside theshell, substantially as described.

i). rl'he combination of the top member and the bottom boiler memberhaving arched plates connected by a reflex curve, the bowplate restingin said curve, the stay secured to the bow-plate and passing through theshell, and a nut and grommet around said stay, substantially asdescribed.

l0. The combination, with the water-chainber, of a closed shell thereinacting as a Waterexcluder, said shell having a steam-pipe to admitsteam-pressure therein.

ll. The combination, with the water-chamber, of a boiler, a man-holeforming a cover therefor, and a shell forming a water eX- cluderattached to said plate, substantially as described.

l2. The combination, with the water-chamber of a boiler, of a man-holeplate, a metallic shell attached to said plate and extending into thewater-space of the boiler, and a steam and a drain pipe connected tosaid shell, substantially as described.

13. The combination, with the boiler member having an arched shell and aflat tubesheet and suitable ends, of a man-hole plate at one end of saidmember, a cylindrical Vessel attached to said plate and extending intothe boiler member, and a steam and a drain pipe connected to saidvessel.

In testimony whereof We affix our signatures in presence of twoWitnesses.

NATHAN B. CLARK.

. FRANK B. KING.

Witnesses:

J. H. WHEELWRIGHT, W. A. BARTLETT.

